When the camera is close enough so the planet is clearly visible, a symbol should be drawn next to it (for example, next to its upper-right corner).
As the camera zooms out, and the planet gets smaller, the symbol should stay at the same size, and always stay next to the the planet.
Once the planet size reaches a certain threshold, the planet itself should no longer be displayed, just its symbol.
Later, this can be extended to include information about the planet (for example size, mass, height and thickness of atmosphere), but for a start, a symbol representing planets (maybe just a filled circle) will be good enough.
Later, this can be extended to include information about the planet (for example size, mass, height and thickness of atmosphere), but for a start, a symbol representing planets (maybe just a filled circle) will be good enough.